1. Technical Field
The present invention relates in general to perpendicular magnetic recording media and, in particulars to an improved system, method and apparatus for onset magnetic oxide layer for high performance perpendicular magnetic recording media.
2. Description of the Related Art
Various forms of exchange-spring and/or capped media have been described for longitudinal media. More recently, this class of media has been the basis of perpendicular recording systems. The basic structure is a granular media layer (CoPtCrB for longitudinal media and CoPtCr-oxide for perpendicular media) that is coupled to a soft layer with relatively strong intergranular exchange. The two layers are either directly exchange coupled (i.e., capped) or the interaction is mediated through a thin exchange coupling layer (i.e., weak-link media).
There are a number of media parameters that may be optimized in an attempt to improve the performance of the recording system. In perpendicular recording systems utilizing continuous media, the capping structure contributes to many, often contradictory, aspects of recording performance. For example, on-track performance can be improved by increasing the exchange interaction between grains, but this improvement often comes at the expense of a broadening of the write width which limits available track density. The nature of the capping material also plays a role in determining both the write field needed to store the data and the resolution that can be achieved when one attempts to read-back the data.
For perpendicular recording the advantages of the two-layer structure are well established. The main advantages are improved writeability, stability and media noise when compared to a single layer granular media. The main disadvantage is relatively poor resolution and, for some cases, increased written track width.
Coercivity (Hc) and signal-to-noise ratio (SNR) of perpendicular media are dependent on the magnetic grain separation. The initial growth of the magnetic layer on the underlayer has a significant contribution to the degree of isolation between magnetic grains, and the control of microstructure in the initial magnetic layer is critical. Thus, enhancing the initial growth of magnetic oxide layers and increasing the magnetic isolation between the grains in the initial magnetic layer would be desirable.